Flow-through conductivity cell



Jan. 23, 1968 w. BREUER FLOW-THROUGH CONDUCTIVITY CELL Filed March 6,1967 ATTORNEYS.

R E w MR TB N m R F L 0 W United States Patent ()fiice 3,365,659Patented Jan. 23, 1968 3,365,659 FLUW-THRGUGH CONDUCTIVITY CELL WolframBreuer, Leverkusen, Germany, assignor to Farbenfahrilren BayerAktiengesellschaft, Leverlrusen-Bayerwerk, Germany, a corporation ofGermany Continuation-impart of application Ser. No. 253,455, Jan. 23,1963. This application Mar. 6, 1967, Ser. No. 620,795 Claims priority,application Germany, Jan. 31, 1962, F 35,886 2 Claims. (Cl. 324-30)ABSTRACT OF THE DISCLOSURE This invention relates to a device for themeasurement of the conductivity of liquids. It more particularly refersto such a device which is adapted to be used with a liquid having phaseinconsistencies, i.e., bubbles or solid matter, therein.

This specification discloses a device comprising a U tube having aninlet take in to the base thereof and two outlet tubes each extendingfrom one arm respectively thereof. The outlet tubes join together abovethe U tube into a single exit tube. The device is utilized in a verticalposition with the inlet tube at the lowest point and the exit tube atthe highest point. The U tube and other portions of this device are soconstructed that no internal surfaces thereof are horizontal ordownwardly directed in the direction of the flow of liquid therethrough.Electrodes are positioned on the inside walls of the U-tube base on eachside thereof separated by the inlet tube communication. These electrodescontact the fluid being tested.

This application is a continuation-in-part of Application Ser. No.253,455, filed J an. 23, 1963, now abandoned.

In order to determine the electrical conductivity of liquids, cellshaving two or more electrodes are used. From the electrical resistivityand the cell constant, it is possible to calculate the specificconductivity of the solution in the cell. For continuous measurement,measuring cells through which the solution flows are used. For smallliquid flows, use is made of microcells having the smallest possiblevolume. Such microcells always have the disadvantage that any bubbles orparticles of dirt which occur in the solution remain adhering at thechanges in crosssection of the cell caused by the electrodes and impairthe measurement. In particular, precision measurements which, becausethe conductivity is greatly dependent on the temperature, necessitate aheat treatment, are severely impaired by the gas bubbles which form onheating. Using the conventional flowthrough microcells, conductivitymeasurement cannot be carried out with the accuracy which is necessary,for example, as in meters for continuously measuring traces of gas witha chemical auxiliary reaction.

It is therefore an object of this invention to provide a conductivitymeasuring cell which is not subject to the disadvantages of prior artcells.

It is another object of this invention to provide a conductivitymeasuring cell capable of measuring the conductivity of liquids whichhave gas bubbles or solid matter such as dirt particles therein.

Other and additional objects of this invention will become apparent froma consideration of this entire specification including the claims anddrawing appended hereto.

In accord with and fulfilling these objects, one aspect of thisinvention includes a device comprising a U tube having an inlet tubeinto the base thereof; an outlet tube extending from each arm of said Utube; and an exit tube attached to both of said outlet tubes. Twoelectrodes are positioned inside the cell in operative association withthe fluid being tested. Each electrode is mounted on the inside of thebase of the U tube on either side of the point in the base where theinlet tube communicates with the U tube. The device of this inventionoperates in a vertical position with the inlet tube being the lowestpoint and the exit tube being the highest point.

Understanding of this invention will be facilitated by reference to theaccompanying drawing in which:

FIG. 1 front elevation partially in section of a device in accord withthis invention; and

FIG. 2 is a sectional view along the line 22 in FIG. 1 looking in thedirection of the arrows.

Referring now to this drawing, a U tube 1 having a base 2 and two arms 3and 4 is provided with an inlet tube 5 into the base 2 thereof and twooutlet tubes 6 and 7 extending from the arms 3 and 4 respectivelythereof. The outlet tubes 6 and 7 join together at a junction 8 to forma single exit tube 9. Electrodes 1i) and 11 are provided on the insidesurface of the U-tube base 2 disposed on either side of the point wherethe inlet tube 5 enters the U tube 1.

In accord with this invention, the device hereof may be made of a singlecontinuous member as shown in the drawing with various portions of thissingle member having the shape and serving the functions set forth. Inthe alternative, some or all of the device described may be made up ofindividual members joined together in the relationship described in aconventional manner.

The cell of this invention is designed and utilized in such manner thatthe inside walls thereof are all upwardly sloping in the direction ofmovement of the liquid passing through the cell for analysis.

Gas bubbles entering the cell move on to the inner curve of the U tubebecause of their buoyancy and the liquid flow, and slide outwardlythereon until they can ascent freely in the slightly sloped arms throughthe outlet tube to the exit tube. This movement outwards is aconsequence of the labile equilibrium of the gas bubbles. Withincreasing displacement outwardly, the lifting component in thedirection of movement becomes greater. Gas bubbles forming in the cellexperience the same movement. Bubbles which form on the electrodes risewithout any hindrance. Due to the particular shaping, the flowcross-section of the cell is doubled by comparison with a simple tube,but the electrical constant of the cell is not substantially reduced. Inmillimeters, the inside diameter of the tube can be 1.5; the distancebetween inlet and outlet can be 30 mm.; the electrodes can be about 5mm. above the inlet; the tubing can have an outside diameter of 6 mm.and the width of the band at the widest point can be 20 mm. Theelectrodes can be platinum.

This microcell is particularly suitable for use in automatic gasanalysis for operation with readily degasifying reaction solutions.

The tubes and other portions of the device of this invention may havesubstantially any cross-sectional shape desired. It is preferred thatthe inside cross-section of the tubes are smooth curves. For economicreasons, these tubes are most desirably round in internal cross-section.The tubes may be made of substantially any substantially electricallyinsulating material, preferably glass, which is substantially inert tothe liquid being passed therethrough as well as to all phaseinconsistencies in said liquid.

What is claimed is:

1. A conductivity measuring cell for measuring the conductivity of aflowing fluid stream, comprising a hollow U tube having an inlet tubeextending from the base thereof, a tube generally symmetricallyextending from each arm of said U tube, which symmetrically jointogether into a top outlet tube, which outlet tube is the 3 member ofsaid cell most remote from said U tube base, and electrodes adjacent toand on each side of said inlet member of said cell most remote from saidU-tube base, :such as to have an exposed contact surface in said U tube,which electrode surfaces are adapted to be operatively associated with atest fluid adapted to be passed through :said U tube, wherein thepassageways of said U tube, the tubes extending therefrom, said outlettube and said inlet =tube communicate with each other; wherein eachexten-' :sion tube and the U tube passageway connected thereto arealigned and have a common axis at least at their point ofinterconnection; and when said cell is positioned with said inlet tubeas the lowermost member and said outlet tube as the uppermost member,all points on the surfaces of all of said tubes are positioned such thatthe next adjacent downstream point thereon is at a greater elevationthan said point. a

2, A cell as claimed in claim 1, wherein the internal cross-sections ofthe members thereof are substantially round.

References Cited UNITED STATES PATENTS 2,640,870 6/1953 Seitz 324-'-3RUDOLPH V. ROLINEC, Primary Examiner. C. F. ROBERTS, Assistant Examiner.

